Photo courtesy of GSK
Eltrombopag (Promacta)
Eltrombopag (Promacta®) in combination with standard immunosuppressive therapy (IST) has received priority review designation from the US Food and Drug Administration (FDA) for first-line treatment of severe aplastic anemia (SAA).
The drug is already approved for SAA in the refractory setting for patients who have had an insufficient response to IST.
And it is approved for adults and children with chronic immune thrombocytopenia (ITP) who are refractory to other treatments and for patients with chronic hepatitis C virus infection who are thrombocytopenic.
Eltrombopag, an oral thrombopoietin receptor agonist, had received breakthrough therapy designation from the FDA earlier this year for use in combination with IST as first-line treatment of SAA.
The priority review designation for the agent as a first-line treatment for SAA is supported by data from a phase 1/2 trial published in NEJM in April 2017 and subsequent data on file with Novartis.
The FDA intends to take action on a priority review application within 6 months of receiving it, rather than the standard 10 months.
The agency grants priority review to applications for products that may provide significant improvements in the treatment, diagnosis, or prevention of serious conditions.
Trial data
Ninety-two patients with previously untreated SAA were enrolled on the trial and received IST and eltrombopag in 3 different cohorts.
Cohorts varied by start day of eltrombopag and duration of eltrombopag therapy. Patients in cohort 1 received eltrombopag from day 14 to 6 months. Patients in cohort 2 received the drug from day 14 to 3 months. And patients in cohort 3 received eltrombopag from day 1 to 6 months.
The overall response rate (ORR) at 6 months was 80% (cohort 1), 87% (cohort 2), and 94% (cohort 3).
The complete response rate at 6 months was 33%, 26%, and 58% in the 3 cohorts, respectively.
At a median follow-up of 2 years, the overall survival rate was 97%.
In the corporate announcement of the priority review designation, Novartis reported an ORR of 85% at 6 months.
Adverse events included transient elevations in liver enzyme levels (7 patients) and 2 severe adverse events—grades 2 and 3 cutaneous eruption—related to eltrombopag that resulted in patients stopping the drug.
Eltrombopag is marketed as Revolade in countries outside the US.